B-37 Mechanisms in determining the orientation of the bat at ball-impact in baseball hitting : Method for calculating contributions of the force-couple system exerted on the bat by the batter's hands

2014 ◽  
Vol 2014 (0) ◽  
pp. _B-37-1_-_B-37-10_
Author(s):  
Yoshitaka MORISHITA ◽  
Toshimasa YANAI
2020 ◽  
Vol 47 (4) ◽  
pp. 338-344
Author(s):  
Aslam Alkadhimi

Correcting severe tooth rotations can be challenging. There are many ways to de-rotate teeth with fixed or removable appliances. Mechanically, the best and most effective way is one that produces a two-force couple system to rotate a tooth around its centre of rotation (longitudinal axis). The aim of this article was to introduce a simple and efficient technique using a closed coil to correct localised tooth rotations in the early alignment stage, utilising a simple two-force couple system. Furthermore, some of the biomechanical principles concerning de-rotation will be revisited.


Author(s):  
Bernardino Javier Sánchez-Alcaraz ◽  
Rafael Martínez-Gallego ◽  
Salvador Llana ◽  
Goran Vučković ◽  
Diego Muñoz ◽  
...  

Racket sports such as padel are characterized by the repetition of unilateral gestures, which can lead to negative adaptations like asymmetries or overuse musculoskeletal injuries. The purpose of this study was to determine the differences in ball impact positions (i.e., forward or backward of the center of gravity) in nine stroke types in a sample of forty-eight recreational male padel players. The sample included 14,478 shots corresponding to 18 matches from six tournaments. Forty-eight male padel players were classified into two groups according to their level: trained (n = 24) and novice (n = 24). Type of stroke and ball impact position were registered using a computerized motion tracking video system. The ball impact position was computed from the distance (cm) between the coordinates of the ball and the player’s center of gravity. Results show that trained players hit the ball in a more backward position (from 11 to 25 cm, compared to novice) in serve and offensive strokes (volleys, trays, and smashes) but used more forward strokes (from 7 to 32 cm, compared to novice) in defensive shots (groundstrokes, wall strokes, and lobs). Because the current differential variables are trainable and demonstrated to be of relevance for performance, the findings of this study may assist padel coaches in designing proper training plans to improve effectiveness and to prevent musculoskeletal injuries regarding the type of stroke and ball impact position. Such knowledge may constitute a very important factor affecting technique, biomechanics, and injury management in padel players of different competitive levels.


Soft Matter ◽  
2021 ◽  
Vol 17 (1) ◽  
pp. 120-125
Author(s):  
Rianne de Jong ◽  
Song-Chuan Zhao ◽  
Diana Garcia-Gonzalez ◽  
Gijs Verduijn ◽  
Devaraj van der Meer

Crater characteristics are compared for droplet and solid ball impact on a granular target at the same effective impact energies.


2009 ◽  
Vol 41 (4) ◽  
pp. 889-897 ◽  
Author(s):  
HIRONARI SHINKAI ◽  
HIROYUKI NUNOME ◽  
MASANORI ISOKAWA ◽  
YASUO IKEGAMI
Keyword(s):  

2014 ◽  
Vol 23 (7) ◽  
pp. e158-e162 ◽  
Author(s):  
Iwein Piepers ◽  
Pieter Boudt ◽  
Alexander Van Tongel ◽  
Lieven De Wilde
Keyword(s):  

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